In the text below I will try to give a short overview over some of the basics when breeding crayfish. Particular species may have other behaviours and demands. It should also be said that my main experience as an aquarist is related to fish, but I will try conveying what little knowledge I’ve got.
Sexing crayfish isn’t always that easy. The genital openings are located on different places on the body depending on whether it’s a male or a female. Males have there genital openings behind/under there posterior pair of legs. Females have their genital openings under the third pair of legs counted from the posterior. However, many individuals have one male as well as one female genital opening, making the sexing much more complicated. But they are always either male or female, usually male but you can’t be sure.
Mating and egg carrying:
In aquarium spawning is possible anytime of the year. The male makes a little sperm packet and places it on the female’s stomach. The female then spawn her eggs passing them trough the sperm packet so that the eggs get fertilized. It is not uncommon for the female to loose a claw during this process. She then places the eggs under her tail where they will be kept until they are ready to be released. How long a period this will be depends on the water temperature and the species, but it will be at least 4 weeks. A lot of other factors can also affect the length of the egg carrying period such as water quality and food supply and quality. The mother will watch over the young a short period after birth.
The fry is very small when they are born but fully developed crayfish. Fry are usually detritus feeders which mean that they will feed on decomposing plant parts and food leftovers they can find while scouring the bottom. Vegetable food is preferred and they can be feed boiled lettuce leaves that are left to decay in the aquarium. Beware of the water quality. Fry is often very cannibalistic and a large aquarium is required if you want I higher number fry to survive. Sorting fry after size may help higher to survival rate.
Crayfish - picture by ncbuckeye
Now you know about their breeding behaviour and how to raise the fry, but how can you get them to breed in the first place? Well, first of all you have to give them the right environment and good food to get them in a condition in which they can spawn. Some species also needs different triggers to breed. These triggers may be a change in the amount of light and number of light hours, a change in temperature, change of circulation etc.
Crayfishes usually accepts most kind of foods and I would recommended feeding them a diet based on boiled lettuce, sinking pellets, shrimps and once or week or so fish meat. This will get them in good condition and help the female survive the spawning period since she usually don’t eat while she is carrying eggs.
Many crayfish species can be kept in relatively small aquariums, but I recommend using larger aquariums since this lower the pressure on the females from the males. The aquarium should be decorated so that a lot of hiding places of suitable size is created. Hiding places can be created using rocks, roots, flowerpots, coconuts, PVC pipes and so on. It’s important that there is at least one, preferably several, hiding places for each crayfish.
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